The medical use of thermal therapy, both hot and cold, is well known to treat various maladies and traumas. Usually, application of heat is used stimulate the body to increase blood flow in an area in order to dissipate the heat build-up. This acts to prevent stiffness in a traumatized joint or appendage. The application of a cold pack reduces swelling and lessens perceived pain. Both of these standard treatments have a place in caring for a patient.
In a hospital or office, thermal appliances may be in stock to apply to various portions of the anatomy. However, in emergency medical services where space and/or weight may be limited, hot and cold treatment is generally restricted to simple containers or absorbent pads, having the desired temperature, applied directly to the affected part of the patient's body. Because of the infinite sizes and shapes of the body, the few thermal devices available do not always conform to the patient in such a way to provide the most effective treatment. To alleviate this problem, small thermal packs have been developed.
To eliminate the problem of maintaining both hot and cold packs at a predetermined temperature for prolonged periods of time, the use of pliant containers enclosing ingredients which, when combined, create an endo- or exo-thermic reaction are used to apply cold or heat to the desired location on the body. However, a by-product of these endo- or exo-thermic reactions is gas. The gas becomes trapped in the container rendering the thermal pack rigid and lacking in the ability to conform to the anatomy. In the extreme, the container may rupture putting the reacting chemicals in direct contact with the patient's body.